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Raybestos Police-Specific Brake Parts

Written by Law and Order Staff

Affinia Under Vehicle Group produces Raybestos® brake pads, rotors and calipers specifically for police vehicles. Its new police-specific rotors were designed to meet or exceed OE rotors by every means of evaluating rotor performance, including wear, noise and pedal feel. These damped iron rotors are an upgrade from the G3000 (OE) iron rotors.

The Police Patrol / Pursuit rotor began as the best rotor Affinia makes; its high carbon damped iron Advanced Technology® rotor and then police-specific internal vanes were added. Damped iron metallurgy with higher carbon content has a greater number and size of graphite flakes than G3000 metallurgy. This higher carbon content with a different micro-structure disrupts harmonic vibrations, suppresses noise from the rotor, and dissipates the heat better.

Raybestos makes rotors with hundreds of internal vane designs, including rotors with the OE-style vanes. In the case of the Patrol / Pursuit rotor, a unique vane design was developed to balance noise and cooling air flow. The vanes allow the air to quickly exit, whether the rotor is mounted on the left side (rotate counter-clockwise) or on the right side (rotate clockwise).

The Raybestos rotor has the mounting flexibility of a non-directional rotor with cooling ability similar to a directional vane rotor. Cooler rotors also have a more solid pedal feel and, of course, have less of a chance for brake fade during aggressive driving. The vented Police Patrol / Pursuit rotor cools off faster than Affinia’s own top-of-the-line Advanced Technology rotor.

For all its special police features, one of the biggest advantages of the Patrol / Pursuit rotor over most replacement rotors is high tolerance machining. Many aftermarket rotors have a lateral runout of 0.004 inch. The Raybestos rotor has a lateral runout of 0.002 inch or less. Excessive runout causes intermittent pad to rotor contact, a thickness variation pedal pulsation most people attribute to “warped rotors” in as little as 3,000 miles.

Finally, the Patrol / Pursuit rotors are mill balanced to within 2 inch ounces. Typical aftermarket rotors are hammer weight balanced within just 3 inch ounces. The Patrol / Pursuit rotor has a smooth surface finish between 15 and 60 Ra (Roughness Average), while many aftermarket rotors have a much rougher surface finish, i.e., between 100 and 160 Ra. A lower Ra results in less brake noise.

Patrol / Pursuit Calipers

Raybestos has just introduced police-specific calipers, which use high temperature silicone dust boots. The dust boot is designed to move with the piston to keep the piston cylinder bore clean and under pressure. If the boot degrades from high temperature, the potential exists for loss of brake system pressure. The OE boot is made of EDPM rubber, which can withstand up to 300 F. This is acceptable for all patrol duties and the majority of pursuits.

However, some police vehicles constantly operate with racing-hot brakes, like EVOC and police academy vehicles. For these vehicles, where the brakes get hot enough to flash or melt EPDM rubber, the answer is calipers with high temperature silicone boots. Silicone can withstand up to 600 F for a sustained period. EPDM will harden and crack after extended exposure to higher temperatures. Silicone boots will remain flexible. A quick inspection of the dust boots on the EVOC car will almost certainly reveal them to be melted, burned, torn, cracked or flaked.

Published in Law and Order, Jun 2010

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